There are numerous types of barriers used to confine hazardous materials and toxic waste in order to prevent environmental damage to the surrounding areas. Leakage of ions and minerals via aqueous diffusion transport through such barriers is unacceptable from an environmental viewpoint.
In recent years, the technology of geophysical barriers has been advanced through use of various ion impermeable materials such as cementitious grouts, polymer barriers, clay barriers, and ice walls. The performance of such engineered barriers has heretofore been measured using monitoring wells. Such an approach is limited inasmuch as the location of a leakage zone is not easily pinpointed and the quantification of the leak is limited, especially in a short term study.
Recently, it has been recognized that the streaming potential can be used to map the flow of liquid in, for example, geophysical strata. In another application of electrical conductivity detection, a sensor system has been developed for use with sheet polymer lined waste disposal and treatment ponds, industrial surface impoundments, basins, and similar containment designs.
This system detects the anomalies in the current density which is the basis for identifying breaches in liners, pipelines and other containment systems holding liquid chemical wastes. Basic electrical parameters (voltage and current) are used to indicate the location of the anomaly. The detection system utilizes five components--a passive sensor, an active current electrode, a monitoring center, connecting cables, and a data acquisition station. In this adaptation, the localized water flow and resultant electrical current carrying anomaly is accomplished by means of migration of soluble ions through the soil/water composite.
In general, this system requires that an impoundment be flooded in order to detect a leak and to permit electrical "coupling" of the passive electrode and the sensing electrode. Furthermore, the flooded pond is necessary in order to provide the leakage of liquid into the soil which in turn presents the electrical resistance anomaly. Thus, this system has limited applications.
There is a need, therefore, for a process for determining the integrity of a geophysical barrier that permits the quantification and localization of any leaks, and that does not require a flooded impoundment system.